The present invention relates to the harvesting of seeds from soil crops and especially to the stripping of seeds from a standing crop while leaving the stems of the crop attached to the ground.
Some soil crops, such as wheat for example, have traditionally been harvested by combines which cut and collect the standing stalks with the head of grain attached, and thereafter separate the grain seeds from the chaff. Although effective, such combines are quite large and costly, due in large part to the high power requirements and the need for providing a separating mechanism capable of separating and handling the large amounts of chaff which are collected.
Other soil crops, such as grass seed for example, have been harvested by machines which employ one or more rotary brushes or other tined rollers which are intended to tear or pull the seeds from the stems. The removed seeds are impelled to a collecting zone, possibly with the aid of an air suction or blowing mechanism. Exemplary of such structures are the disclosures in U.S. Pat. No. 1,134,443 issued to Engle on Apr. 6, 1915; U.S. Pat. No. 1,206,409 issued to Bruce on Nov. 28, 1916; and U.S. Pat. No. 2,460,029 issued to Ramp on Jan. 25, 1949.
In an earlier proposal of E. Cordell Lundahl, disclosed in an earlier U.S. patent application Ser. No. 371741, filed Apr. 26, 1982, a harvesting machine has been described in which upper and lower rotary brushes are mounted axially transverse and define a bite within which the crop heads are engaged by the brush bristles. The ends of the bristles are randomly and closely spaced along the brush periphery in the longitudinal and circumferential directions to present a substantially "solid" face to the crop. A rear air stream is directed upwardly from behind the brushes to carry off stripped seeds. A front air stream is directed rearwardly against crop stems located ahead of the brushes to bend the stems toward the bite. The seeds are stripped from the crop heads by a rubbing action of the bristles against the crop heads, whereas the crop stems remain attached to the ground. Although such a proposal offers significant advantages over traditional harvesting techniques which involve the handling of significantly greater amounts of chaff, substantial room for improvement remains. For example, the engagement of the crop heads by the bristle tips within the bite may tend to pinch off not only the seeds, but possibly the crop heads themselves and even parts of the stem, especially since the stem does not have a convenient "escape" route through the brush. Moreover, since stripping occurs within the bite, the height adjustment of the brushes relative to the crop height is very sensitive.
It has also been heretofore proposed to apply a "beating" concept to a grain harvesting machine as described for example in U.S. Pat. Nos. 2,495,417 and 2,620,614 issued to Mc Connel et al on Jan. 24, 1950 and Dec. 9, 1952, respectively. In the machine disclosed in the Mc Conel et al patents, discs are spaced along a horizontal rotary shaft so that as the machine advances through the crop, heads of grain are able to pass between the discs. Wedge elements carried by faces of the discs impact upwardly against the grain heads as the discs rotate. The wedge elements are inclined vertically and slam the heads sideways against the face of an adjacent disc. Such slamming action is intended to knock grain seeds from the head, while leaving the stem in the ground. In order to collect the separated grain kernels, blades are mounted at outer edges of the discs (or rods) to generate a rearward air stream to entrain the kernels and direct them to a collecting zone. It has also been proposed in U.S. Pat. No. 2,749,916 issued to Mc Connell on June 12, 1956, to use bent rods of circular cross section in lieu of discs. The above-described machine has not, however, been commercially successful due in part to its inability to perform acceptably in relatively short standing crops.
Numerous other grain harvesters have been proposed which involve a rotary beater intended to strike the grain heads in some fashion to separate the grain from the stalk. Exemplary of such machines are the disclosures in the following U.S. Pat. Nos. 781,662 issued to Kistler on Feb. 7, 1905; 1,418,542 issued to Dill on June 6, 1922; 2,547,749 issued to Gray on Apr. 3, 1951; 2,627,713 issued to Manning on Feb. 10, 1953; 3,184,904 issued to Fiedler on May 25, 1965; 2,853,845 issued to Smith on Sept. 30, 1958; 3,184,905 issued to Hillier on May 25, 1965; and French Pat. No. 1,240,440 issued Nov. 17, 1959. However, none of those proposals has achieved commercial success.